It is known that for the elderly a respiratory infection such as a cold or influenza, or a gastrointestinal infection such as a norovirus infection can be fatal. Furthermore, in recent years it has been pointed out that for pregnant women there is a risk of her baby developing congenital disease due to rubella infection, and prevention of this infection is needed not only for those who are pregnant but also for people in the community around the pregnant women. Vaccination is useful for the prevention or treatment of various infections in such elderly people, pregnant women, and children and, furthermore, for the prevention or as a counter-measure against serious progression of influenza or bacteria.
Moreover, for a young adult such as a student, the immunological function is usually high, but awareness of protection against infection by means such as vaccination is low; it is known that even for a young adult, immunocompetence is degraded by mental stress, etc. and the person will easily catch an infection, and there is a need to enhance immunocompetence regardless of the age group. However, the antibody titer is not sufficiently increased by vaccination alone, the period during which the effect continues is short, the effect can thus not be fully obtained, and research is being carried out into various vaccine adjuvants.
Vaccine is a general term for antigens that are used to actively immunize humans or animals. There are live vaccines employing an attenuated live pathogen, inactivated or killed vaccines employing a dead virus or pathogenic bacterium, component vaccines employing constituent components thereof, and toxoids, which are inactivated substances of a toxin produced by a bacterium. Furthermore, as vaccines there are cancer vaccines, which are used in the treatment of a cancer, and employ an antigen (cancer antigen) that is not expressed in a normal cell but is specifically expressed only in a cancer cell.
An anti-infection agent containing, as an active ingredient, a fraction that has a molecular weight of at least 1,000 but no greater than 200,000 from water-soluble fractions obtained by fermentation of the rhizome of the Dioscoreaceae Dioscorea plant has been proposed (Patent Document 1).
Furthermore, for the purpose of strengthening immunocompetence, an immunoadjuvant that is nasally administered together with an immunogenic substance and that contains, as an active ingredient, a cultured composition obtained from a culture of a microorganism of the aureobasidium genus (Aureobasidium sp.) has been proposed (Patent Document 2).
Moreover, there have been proposed a food that contains, per 100 g of food, at least 106 counts of Lactobacillus rhamnosus GG and at least 0.5 g of β-glucan isolated from a natural source, and the use thereof as an adjuvant for enhancing the immunoresponse to a vaccine (Patent Document 3).
Furthermore, it has been reported that the antibody titer specific to a vaccine strain increased significantly when a healthy elderly subject of 70 years age or older undertook oral ingestion of a yoghurt drink containing Lactobacillus casei DN-114 001 every day for 4 weeks before being immunized with an influenza vaccine compared with the case of oral ingestion of a placebo non-fermented milk drink (Non-Patent Document 1).
Moreover, it has been reported that influenza-specific IgA was increased by oral ingestion of Lactobacillus fermentum CECT5716 cells (Non-Patent Document 2).
Furthermore, it has been reported that influenza-specific IgG, IgG1, and IgG3 were increased by oral ingestion of a sour milk drink containing Bifidobacterium animalis ssp. lactis (BB-12®) cells and L. paracasei ssp. paracasei (L. casei 431®) (Non-Patent Document 3).
Moreover, it has been reported that acidic polysaccharides produced by Lactobacillus delbrueckii ssp. bulgaricus OLL1073R-1 and fermented milk produced using, as a starter bacterium, Lactobacillus delbrueckii ssp. bulgaricus OLL1073R-1 have an NK cell activation effect (Patent Document 4).